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Biomedical subjects

Bon Kimura

Publications and source records attributed to Bon Kimura.

9 recordsLinked to original sources
PubMed2005

[Growth inhibition of Vibrio parahaemolyticus in seafood by tabletop dry ice cooler].

Tabletop dry ice coolers (three types; dome model, cap model and tripod model), which are used in kitchens and hotel banquet halls to refrigerate fresh seafood, were investigated to determine whether growth of Vibrio parahaemolyticus was inhibited by their use. On TSA plates containing 1.8% NaCl and fresh seafood (fillets of squid, pink shrimp and yellowtail), V. parahaemolyticus (O3:K6, TDH+) inoculated at 4 to 5 log CFU/sample and left at ambient temperature (25 degrees C) grew by 1.0 to 2.8 orders in 4 hours. In contrast, with tabletop coolers no significant increase in viable count occurred in 3 to 4 hours, confirming that tabletop coolers inhibited the growth of V. parahaemolyticus. The temperature in each tabletop cooler was kept below 10 degrees C for 80 to 135 min, though the CO2 gas concentration in them remained high for only a short time (0 to 75 min). It was presumed that the refrigeration function mainly contributed to growth inhibition. Our results indicate that tabletop dry ice coolers are helpful for prevention of food-borne disease due to V. parahaemolyticus in food-service locations, such as kitchens and banquet halls.

Dry Ice↗
PubMed2005

Incidence of Listeria monocytogenes in raw seafood products in Japanese retail stores.

The incidence of Listeria monocytogenes in raw fish, shellfish, and fish roe was investigated in seafood products collected from randomly selected retail stores in and around Tokyo, Japan. Of the 10 samples of 208 examined found positive for L. monocytogenes by mini-VIDAS LMO, seven were fish roe (cod, salmon) and three were minced tuna. Three serotypes (1/2a, 1/2b, 3b) were detected among the isolated strains; serotype 1/2a was predominant (8 of 10).

Animals↗
PubMed2005

Growth and toxin production by Clostridium botulinum in steamed rice aseptically packed under modified atmosphere.

Sales and consumption of ready-to-eat aseptic steamed rice products have increased manyfold in Japan over the past 10 years. To determine the safety of steamed rice (water content 60%, pH 6.5) aseptically packaged under modified atmosphere, challenge studies were performed using a mixture of Clostridium botulinum proteolytic strains (five strains of type A and five strains of type B). Atmospheric conditions of 0 and 15% oxygen (with 5% CO2 and 5% N2 as the balance) were used. No neurotoxins were detected, and organoleptically acceptable conditions persisted for 24 weeks at 15% oxygen conditions. However, botulinum neurotoxin was found in one of three samples at 12 weeks and in one of two samples at 24 weeks at 0% oxygen and 30 degrees C. When samples were inoculated with C. botulinum with amylase (0% oxygen), neurotoxin and sample spoilage was detected after only 1 week of storage. Challenge studies using proteolytic strains of C. botulinum mixed with Bacillus subtilis (amylase formers) also were performed with atmosphere conditions of oxygen at 0, 5, 10, and 15% (with 5% CO2 and 5% N2 as the balance). Under 10 and 15% oxygen conditions, neurotoxin was not detected after 1 week of storage, but sample spoilage was detected after the same period. Under 0% oxygen conditions, neurotoxin was detected at 1 week, but the sample remained organoleptically acceptable even after 2 weeks of storage. Both neurotoxin and sample spoilage were detected at 1 week of storage under 5% oxygen conditions. Based on these results, cocontamination of amylase-producing Bacillus with C. botulinum would increase the risk of foodborne botulism when aseptic rice samples are packed under low-oxygen conditions (<5%). Therefore, to ensure the safety of these products, packing under atmospheric containing more than 10% oxygen is recommended.

Botulinum Toxins↗
PubMed2004

Detection of Leuconostoc strains at a meat processing plant using polymerase chain reaction.

To simplify the labor-intensive conventional routine testing of samples to detect Leuconostoc at a meat processing plant, we developed polymerase chain reaction (PCR) primers specific for Leuconostoc from 16S rRNA gene sequences. These primers did not detect other common lactic acid bacteria such as Lactobacillus plantarum, Lact. sake, Lact. fermentum, Lact. acidophilus and Weissella viridescens. PCR with this primer detected all Leuconostoc species tested (Leu. mesenteroides subsp. mesenteroides, Leu. pseudomesenteroides, Leu. carnosum, Leu. lactic, Leu. citreum, Leu. amelibiosum, Leu. gelidum), except for Leu. fallax, and no other lactic acid bacteria on agarose gel electrophoresis. The method could identify areas contaminated with Leuconostoc in a large-scale industrial meat processing plant. Of 69 samples analyzed, 34 were positive for Leuconostoc according to the conventional culture method (isolation of LAB producing dextran) and PCR, whereas 29 were negative according to both. Six samples were culture-negative but positive by PCR. No false negative results were generated by PCR. The method is rapid and simple, is useful for routinely monitoring areas contaminated with Leuconostoc in meat processing plants, and could help to prevent the spoilage of meat products.

DNA Primers↗
PubMed2004

Mechanism of the decrease of tetrodotoxin activity in modified seawater medium.

This study was designed to clarify the mechanism of the decrease of tetrodotoxin (TTX) toxicity during storage in a modified seawater medium (MSWM). When TTX was added to sterilized MSWM, the toxicity of TTX in the medium markedly decreased within 1 day, as determined by a mouse bioassay. HPLC (high-performance liquid chromatography) analysis showed that the peak of TTX was reduced and new unidentified peaks were observed. Omission of the P-1 metal solution from MSWM suppressed the decrease in TTX toxicity and the disappearance of TTX. Further studies indicated that boric acid in the P-1 metal solution triggers this toxicity decrease, indicating that TTX is chemically, not microbiologically, converted to unknown compounds in MSWM.

Animals↗
PubMed2004

Direct detection and identification of lactic acid bacteria in a food processing plant and in meat products using denaturing gradient gel electrophoresis.

We established a novel system using denaturing gradient gel electrophoresis (DGGE) to quickly identify bacteria known to be responsible for spoilage in meat processing plants and meat products. We extracted bacterial DNA from swabbed samples at various locations in the plant and from meat products and performed PCR amplification, targeting 16S rDNA from the dominant organisms. The amplification products were subjected to DGGE, and the contaminating bacteria in the meat products and the plant were analyzed. This analysis indicated that lactic acid bacteria and spoilage-causing bacteria are widely distributed within the meat processing plant. We developed molecular size markers to identify the dominant organisms obtained from the plant and meat products. The establishment of the present method allows quick and simple identification of bacteria causing the possible deterioration of products and contamination and thus permits constant monitoring of any harmful bacteria within meat processing plants.

Animals↗
PubMed2003

Cloning and sequencing of the histidine decarboxylase genes of gram-negative, histamine-producing bacteria and their application in detection and identification of these organisms in fish.

The use of molecular tools for early and rapid detection of gram-negative histamine-producing bacteria is important for preventing the accumulation of histamine in fish products. To date, no molecular detection or identification system for gram-negative histamine-producing bacteria has been developed. A molecular method that allows the rapid detection of gram-negative histamine producers by PCR and simultaneous differentiation by single-strand conformation polymorphism (SSCP) analysis using the amplification product of the histidine decarboxylase genes (hdc) was developed. A collection of 37 strains of histamine-producing bacteria (8 reference strains from culture collections and 29 isolates from fish) and 470 strains of non-histamine-producing bacteria isolated from fish were tested. Histamine production of bacteria was determined by paper chromatography and confirmed by high-performance liquid chromatography. Among 37 strains of histamine-producing bacteria, all histidine-decarboxylating gram-negative bacteria produced a PCR product, except for a strain of Citrobacter braakii. In contrast, none of the non-histamine-producing strains (470 strains) produced an amplification product. Specificity of the amplification was further confirmed by sequencing the 0.7-kbp amplification product. A phylogenetic tree of the isolates constructed using newly determined sequences of partial hdc was similar to the phylogenetic tree generated from 16S ribosomal DNA sequences. Histamine accumulation occurred when PCR amplification of hdc was positive in all of fish samples tested and the presence of powerful histamine producers was confirmed by subsequent SSCP identification. The potential application of the PCR-SSCP method as a rapid monitoring tool is discussed.

Amino Acid Sequence↗
PubMed2002

Phylogenetic study of the genus Oceanospirillum based on 16S rRNA and gyrB genes: emended description of the genus Oceanospirillum, description of Pseudospirillum gen. nov., Oceanobacter gen. nov. and Terasakiella gen. nov. and transfer of Oceanospirillum jannaschii and Pseudomonas stanieri to Marinobacterium as Marinobacterium jannaschii comb. nov. and Marinobacterium stanieri comb. no.

The phylogenetic relationships of Oceanospirillum strains were analysed by using the nucleotide sequences of 16S rRNA and gyrB genes. Results from sequence analysis demonstrated that the Oceanospirillum core group consisted of four species, Oceanospirillum linum, Oceanospirillum maris, Oceanospirillum beijerinckii and Oceanospirillum multiglobuliferum, with enough distance to separate them as different species. However, four other Oceanospirillum species occupied taxonomic positions separate from the Oceanospirillum core group: Oceanospirillum jannaschii, Oceanospirillum japonicum and Oceanospirillum kriegii in the gamma-Proteobacteria and Oceanospirillum pusillum in the alpha-Proteobacteria. Oceanospirillum jannaschii clustered with Marinobacterium georgiense, Pseudomonas iners and Pseudomonas stanieri on the basis of phylogenetic analysis of 16S rRNA and gyrB genes. The other three species did not cluster with known genera. Also, the sequence similarity values of the gyrB genes between the three subspecies of Oceanospirillum maris and those between the two subspecies of Oceanospirillum beijerinckii were above 99%. The close relationships between the subspecies of Oceanospirillum maris and of Oceanospirillum beijerinckii were further supported by similar physiological properties and high DNA-DNA hybridization values, suggesting that these subspecies should not be regarded as valid. From these results, Oceanospirillum sensu stricto should be defined to consist of Oceanospirillum linum, Oceanospirillum maris, Oceanospirillum beijerinckii and Oceanospirillum multiglobuliferum. We propose to create the following new genera: Pseudospirillum gen. nov. for Oceanospirillum japonicum as Pseudospirillum japonicum comb. nov.; Oceanobacter gen. nov. for Oceanospirillum kriegii as Oceanobacter kriegii comb. nov.; and Terasakiella gen. nov. for Oceanospirillum pusillum as Terasakiella pusilla comb. nov. The transfer is proposed of Oceanospirillum jannaschii and Pseudomonas stanieri to Marinobacterium as Marinobacterium jannaschii comb. nov. and Marinobacterium stanieri comb. nov. Furthermore, Pseudomonas iners should be reclassified as a strain of Marinobacterium georgiense. Finally, the subspecies of Oceanospirillum maris (O. maris subsp. maris, O. maris subsp. hiroshimense and O. maris subsp. williamsae) and Oceanospirillum beijerinckii (O. beijerinckii subsp. beijerinckii and O. beijerinckii subsp. pelagicum) should be combined as Oceanospirillum maris and Oceanospirillum beijerinckii, respectively.

Alphaproteobacteria↗